On Tue, 12 May 2020 17:33:06 GMT, Rony G. Flatscher
<github.com+60214806+rony...@openjdk.org> wrote:
>> Suggested CSR:
>>
>> Summary
>> =======
>> Have javafx.fxml.FXMLLoader compile FXML scripts before evaluating them, if
>> the script engine
>> implements the javax.script.Compilable interface to speed up execution. In
>> case compilation
>> throws a javax.script.ScriptException fall back to evaluating the uncompiled
>> script. Allow
>> control of script compilation with a "compile" PI for FXML files.
>>
>> Problem
>> =======
>> javafx.fxml.FXMLLoader is able to execute scripts in Java script languages
>> (javax.script.ScriptEngine implementations) referred to or embedded in a
>> FXML file.
>>
>> If a script engine implements the javax.script.Compilable interface, then
>> such scripts could be
>> compiled and the resulting javax.script.CompiledScript could be executed
>> instead using its
>> eval() methods.
>>
>> Evaluating the javax.script.CompiledScript objects may help speed up the
>> execution of script
>> invocations, especially for scripts defined for event attributes in FXML
>> elements (e.g. like
>> onMouseMove) which may be repetitively invoked and evaluated.
>>
>> Solution
>> ========
>> Before evaluating the script code test whether the javax.script.ScriptEngine
>> implements
>> javax.script.Compilable. If so, compile the script to a
>> javax.script.CompiledScript object first
>> and then use its eval() method to evaluate the script, otherwise continue to
>> use the
>> javax.script.ScriptEngine's eval() method instead. Should compilation of a
>> script yield
>> (unexpectedly) a javax.script.ScriptException then fall back to using the
>> javax.script.ScriptEngine's eval() method. A new process instruction
>> "compile" allows control of
>> the compilation of scripts ("true" sets compilation on, "false" to set
>> compilation off) in FXML
>> files.
>>
>> Specification
>> =============
>> If a javax.script.ScriptEngine implements the javax.script.Compilable
>> interface, then use its
>> compile() method to compile the script to a javax.script.CompiledScript
>> object and use its
>> eval() method to run the script. In the case that the compilation throws
>> (unexpectedly) a
>> javax.script.ScriptException log a warning and fall back to using the
>> javax.script.ScriptEngine's eval() method instead.
>> To allow setting this feature off and on while processing the FXML file a
>> "compile" process
>> instruction ("<?compile false?>" or "<?compile true?>") gets defined that
>> allows to turn
>> compilation off and on throughout a FXML file.
>
> Doc addition for the CSR:
> =================
> The following text was added to the [Introduction to
> FXML](https://github.com/openjdk/jfx/blob/master/modules/javafx.fxml/src/main/docs/javafx/fxml/doc-files/introduction_to_fxml.html)
> at two locations, the "Script Event Handlers" ("#script_event_handlers") and
> the "Scripting" (#scripting") sections:
>> <p>Hint: to turn off automatic compilation of script code place the
>> processing instruction <span
>> class="code"><?compile false?></span> before the script. To turn on
>> compilation of script code again use the
>> processing instruction <span class="code"><?compile true?></span> (or
>> short: <span
>> class="code"><?compile?></span>). The compile processing instruction
>> can be used repeatedly to turn compilation
>> of script code off and on.</p>
>
> This documents the compile processing instruction, that it compilation is on
> by default and that it can be turned off
> and on repeatedly. It is hoped that this formulation plays well with the
> context where this paragraph got introduced.
Doc addition for the CSR (update)
-------------------------------------
In the event handler section:
> <p>Note: to turn off automatic compilation of script code place the
> processing instruction <span
> class="code"><?compile false?></span> before the element that contains
> the script. To turn on compilation of
> script code again use the processing instruction <span
> class="code"><?compile true?></span> (or short: <span
> class="code"><?compile?></span>). The compile processing instruction
> can be used repeatedly to turn compilation
> of script code off and on.</p>
In the Scripting section:
> <p>Note: to turn off automatic compilation of script code place the
> processing instruction <span
> class="code"><?compile false?></span> before the script element. To
> turn on compilation of script code again use
> the processing instruction <span class="code"><?compile true?></span>
> (or short: <span
> class="code"><?compile?></span>). The compile processing instruction
> can be used repeatedly to turn compilation
> of script code off and on.</p>
-------------
PR: https://git.openjdk.java.net/jfx/pull/192
